1. Field of the Invention
Embodiments of the present invention relate to a power supply, an image forming device, and a power supply method.
2. Description of the Related Art
Due to growing awareness of environmental problems in recent years, power saving has been required for various devices. Even in various types of standards, regulations on power consumption during power saving modes have been reinforced.
As a method of achieving power saving in various devices, for example, it has been considered to shut down power supply to the systems that are not used during a standby mode, and also to terminate the portions within a device that are not used during the standby mode. Additionally a method has been considered in which a main CPU is terminated during the standby mode by introducing an IC which is dedicated for network responses.
Unfortunately, for a case of generating a direct current voltage from a commercial alternating-current power supply, in general, the efficiency is reduced as the value of the direct current voltage to be generated is lowered. Since the efficiency of generating a low voltage, which is supplied to a load during the power saving mode, is reduced, even if the power consumption during the standby mode is reduced in the devices, it is not always true that the power saving is achieved.
Patent Document 1 discloses, for example, a power supply that can reduce an amount of power consumption during a power saving mode. In the power supply, a switching regulator and a series regulator are arranged in parallel. During a normal operating mode, the switching regulator is utilized. That is because the efficiency of the switching regulator is better. During the power saving mode, since an amount of the power consumed inside the series regulator is small, the series regulator is utilized.
Patent Document 1: Japanese Patent Laid-Open Application No. 2004-88853